Effects of different processing methods on phenolic compounds in flaxseed meal

Area of Science:

• Agricultural Science
• Food Science
• Nutritional Science

Background:

• Flaxseed meal is rich in phenolic compounds, which possess antioxidant properties.
• Processing methods can alter the profile and bioavailability of these compounds.
• Understanding these effects is crucial for optimizing flaxseed utilization.

Purpose of the Study:

• To investigate the impact of different processing methods on the phenolic compound content and composition of flaxseed meal.
• To identify optimal processing conditions for maximizing beneficial phenolic compounds.

Main Methods:

• Supercritical fluid extraction (SE) treatment under varying pressures and times.
• Extrusion processing at specific moisture content, temperature, and frequency.
• Fermentation using *Bacillus subtilis* for a defined period.
• Quantification of total flavonoids, phenolic acids, specific compounds (e.g., rutin, protocatechuic acid, gallic acid, vanillic acid), and secoisolariciresinol diglucoside (SDG).

Main Results:

• Supercritical fluid extraction (SE) at 1.0 MPa for 3 min increased total flavonoids by 2.26 times and phenolic acids by 1.63 times compared to the control. Erucic acid content also increased by 85.76%.
• Optimal extrusion conditions (15% moisture, 140°C, 29 Hz) resulted in the presence of rutin and a 2.81-fold increase in protocatechuic acid.
• Fermentation with 3% *Bacillus subtilis* for 4 days produced bound gallic acid and free vanillic acid, with a 40.65% increase in protocatechuic acid.
• Extrusion processing yielded the highest overall phenolic compound levels in flaxseed meal.
• All tested processing methods significantly increased the secoisolariciresinol diglucoside (SDG) content compared to the control.

Conclusions:

• Different processing methods significantly alter the phenolic content and composition of flaxseed meal.
• Extrusion processing appears to be the most effective method for enhancing overall phenolic compounds.
• SE treatment and fermentation also offer specific benefits in terms of individual phenolic acid profiles and compound increases.